Alternator ????
Thread Starter
Burning Brakes
Joined: Oct 2004
Posts: 925
Likes: 4
From: EXTON PA
Alternator ????
Took out by 98 coupe stock corvette and I noticed that the charging gauge was dropping from 13+ to 12 when in low rpms when I started to move and rpm went up the level moved from 12 to 13+. Is my alternator shot? Belts look good - installed Goodyear Gators late year at the start of the summer. My head lights did not seem to drop the brightness level during the charging gauge drop to 12.
Any input would be appreciated. If the alternator is shot does anybody have recommendions on sources for new manuactured alternators. I have Gene's number and site at GmPartsHouse.
Thanks
Any input would be appreciated. If the alternator is shot does anybody have recommendions on sources for new manuactured alternators. I have Gene's number and site at GmPartsHouse.
Thanks
Le Mans Master
Joined: Sep 2003
Posts: 8,847
Likes: 795
From: Longview Texas
As the battery charges, and if there are heavy loads on the alternator (cooling fans, etc.), the voltage can drop to mid 13s, but I don't think it should ever drop all the way to 12 volts.
Did you check your battery to make sure it is charging? It may have a cell going bad or some other internal problem
If battery is good, have a shop check the alternator. They should be able to test the alternator just like the battery.
There are still shops around that will rebuild alternators and starters for a lot less than a new one. It may just be the voltage regulator going bad.
Did you check your battery to make sure it is charging? It may have a cell going bad or some other internal problem
If battery is good, have a shop check the alternator. They should be able to test the alternator just like the battery.
There are still shops around that will rebuild alternators and starters for a lot less than a new one. It may just be the voltage regulator going bad.
Thread Starter
Burning Brakes
Joined: Oct 2004
Posts: 925
Likes: 4
From: EXTON PA
As the battery charges, and if there are heavy loads on the alternator (cooling fans, etc.), the voltage can drop to mid 13s, but I don't think it should ever drop all the way to 12 volts.
Did you check your battery to make sure it is charging? It may have a cell going bad or some other internal problem
If battery is good, have a shop check the alternator. They should be able to test the alternator just like the battery.
There are still shops around that will rebuild alternators and starters for a lot less than a new one. It may just be the voltage regulator going bad.
Did you check your battery to make sure it is charging? It may have a cell going bad or some other internal problem
If battery is good, have a shop check the alternator. They should be able to test the alternator just like the battery.
There are still shops around that will rebuild alternators and starters for a lot less than a new one. It may just be the voltage regulator going bad.
New Battery is in place. In my area all the shops that use to rebuild are gone. Also is not this alternator requiring special specs that are not easy to rebuild/remanufacture. Higher output ??????
Burning Brakes
Joined: Jun 2005
Posts: 782
Likes: 45
From: Toronto Ontario
It sounds like the voltage regulator might be on the way out. Under normal conditions (when not everything is turned on at once), the alternator output should be regulated to just over 14V. Even at idle. Even with an underdrive pulley. One of the stator windings or a rectifier diode might be shorted as well. Any mechanical shop with a scope can get to the bottom of this in no time. A new regulator/rectifier can be put into the alternator at home. I've done a bunch over the years and saved a lot of $$$.
Melting Slicks
Joined: Feb 2006
Posts: 3,105
Likes: 96
From: Sunrise FL
I have a '99 with similar (low) voltages. Starting up would be around 12.9, then creep up to mid 13's which was still low. Found loose wires (fat reds) at the fuse box, and corroded neg bat terminal. Also cleaned grounds at the two front multiple ground plugs.
Also had my local rebuilder closeup shop
Now its hi 13's, about right. But will scope alt further, it still drops at idle
Also had my local rebuilder closeup shop
Now its hi 13's, about right. But will scope alt further, it still drops at idle
Last edited by mikem350; Jul 14, 2009 at 09:47 PM.
